In the predawn hours two weeks into 2006, a manmade meteor will blaze down in a fireball, pop open a chute and leave a canister melting a hole in Utah’s high desert snow.

Sealed inside is ancient stardust collected two years ago Monday from the tail of a passing comet. The canister could hold the starting recipe of our solar system and perhaps clues to how life started on Earth.

For those scientific gems, almost 150 scientists worldwide are waiting to intensely examine perhaps a million dust particles so tiny that all of them bunched together would weigh less than a hundredth of a raisin and fit inside this letter: “O.”

“I’m confident that the particles will be the most primitive stuff we’ve ever had on earth,” said University of Washington astronomy professor Donald Brownlee, lead scientist for NASA’s Stardust mission.

Stardust sounds magical, and since humans are made of the stuff, there is a temptation to crow, as Crosby, Stills, Nash & Young did, that “we are golden.” The truth is less glamorous — much of it is sooty carbon blasted out of dying stars.

“It’s literally dirt,” said John Bradley, director of the Institute of Geophysics and Planetary Physics at Lawrence Livermore National Laboratory. “It’s basically cosmic grime.”

But the stardust landing in Utah on Jan. 15 is probably the preserved legacy of a cloud that coalesced 4.6 billion years ago into the sun, its planets and planetoids and every living thing — including us.

Over time, planets change so much that every molecule is broken and rearranged — the Earth and its moon, for example, once were covered in seas of hot magma — so planetary bodies are virtually useless to scientists trying to understand where we came from.Comets, on the other hand, live in the dark, cold and relatively uneventful reaches of the solar system and are thought to be frozen leftovers from its formation, locking its original ingredients and their amounts in ice. Many scientists suspect that comets delivered both water and the complex building molecules of life to an otherwise rocky and barren young Earth.

Every once in a while, a comet is nudged into a new orbit near the sun. Comet Wild-2 (pronounced VILT-2) swung inward a million years ago and got an extra kick toward Mars in 1974. In February 1999, NASA and the Jet Propulsion Laboratory at Caltech sent a desk-sized spacecraft almost two billion miles to meet it.

The craft was named Stardust, and while it featured cameras and instruments, the craft amounted to a sophisticated catcher’s mitt. Engineers built the glove itself as a honeycomb full of the lightest manmade substance, a kind of fluffy glass called aerogel. Starting on New Year’s Eve two years ago, Stardust slipped into the tail of Comet Wild-2 about halfway to Jupiter. The craft opened its glove and entered a brutally punishing bombardment.

Scientists figured a couple places on the comet, warming as it drew toward the sun, would spout gases, rock and particles. Instead, more than 20 supersonic jets erupted from Wild-2 and sandblasted the Stardust craft even though it was 150 miles away, with millions of particles hitting at six times the speed of a rifle bullet.

That the craft survived is partly a credit to designers of its shields and partly luck.

Now Stardust is returning to Earth and will release its sample return canister for the fastest re-entry in the history of the U.S. space program, about 12 kilometers per second.

If the hot canister cracks and lets in any melting snow, the aerogel could soften. Outdoor air could contaminate the dust. Scientists plan to fly the canister to Johnson Space Center in Houston, where two days later it will be opened in a clean room. Then they will find out how well the catcher’s mitt worked.

The stardust particles create tiny tracks into the aerogel, and at least some tracks will be carved out of the aerogel using ultrasonic diamond blades invented for that purpose at Livermore Lab. In some cases, scientists will steer down the tracks and gather the particles with a microscopic needle.

“To put it literally, we do a colonoscopy,” Livermore’s Bradley said.

Samples of tracks and particles both whole and in slices will be sent around the world, but a great deal of the analysis will be done in the Bay Area, Brownlee said, at the University of California, Berkeley, at Stanford’s Linear Accelerator Center, at NASA Ames in Mountain View and at Lawrence Livermore Lab, where a vast array of high-tech instruments includes one of the world’s most advanced electron microscopes.

In each case, scientists expect to press the limits of technology to divine the origins of the solar system from specks of dust.

“I think in the end we’ll be able to answer a lot of questions about whether these are really representative materials from which everything in the solar system was made,” said NASA Ames research astrophysicist Scott Sandford.

He leads an international effort to examine the organic compounds that could make up a third of the dust, though organics are easily destroyed or changed by impacts with the aerogel. A small amount will be amino acids that, chained together, can form peptides and proteins. Scientists are keenly interested in how complex and how abundant these organic molecules are, because the greater quantity of complex organic molecules, the greater the foundations for the emergence of life.

Knowing those answers could help settle whether life on Earth arose because the planet and solar system are unique or whether the conditions for seeding life here are as common in the universe as, well, dirt.

“That’s the question,” Bradley said. “Are we typical? Or is this solar system the one-in-100 million morphology?”

“If this stuff is abundant,” said NASA’s Sandford, “then it increases the likelihood that life is abundant. But if not, then it depends more on the conditions on the surface of the planet. In any event, it strikes me that the odds are not bad that there’s a lot of life out there.”

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